Hanyang Med Rev.  2014 Aug;34(3):100-106. 10.7599/hmr.2014.34.3.100.

Understanding the Human Sensory Conduction of Smell

Affiliations
  • 1Department of Otorhinolaryngology-Head and Neck Surgery, Dongguk University Medical Center, Goyang, Korea. sw43857@dumc.or.kr

Abstract

The olfactory epithelium is the main end organ for the sense of smell in humans and vertebrates. Specially differenciated neuronal cells called olfactory receptor neurons (ORNs) play a key role in the olfactory epithelium by expressing the olfactory receptors (ORs) on their apical surface membrane. The ORs are G-protein coupled receptors that transmit signals from odorants to ORNs by molecular cascades using cyclic adenosine monophosphate, calcium ions and other molecules, which result in the depolarization of ORN. Unlike other mammalian animals, only about 30% of OR genes in the human genome are expressed. The Nobel Prize was awarded to the scientists who cloned these ORs for the first time. Each ORN expresses only a single type of OR, and ORNs which express the same type of OR converge together into the same glomeruli in the olfactory bulb. A single OR recognizes multiple odorants, and a single odorant is recognized by multiple ORs with varying affinities. At the higher neurons beyond the bulb, neuronal connections are divergent. The combinatorial model of odor identification and discrimination is well established at the convergence level, but little is known about the action mechanisms of neuronal divergence for odor identification and discrimination and further study is required.

Keyword

Olfactory Mucosa; Olfactory Pathways; Olfactory Receptor Neurons; Receptors, Odorant
Full Text Links
  • HMR
Actions
Cited
CITED
export Copy
Close
Share
  • Twitter
  • Facebook
Similar articles
Copyright © 2021 by Korean Association of Medical Journal Editors. All rights reserved.     E-mail: koreamed@kamje.or.kr